From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1BABC43387 for ; Fri, 4 Jan 2019 18:02:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82FD3218D3 for ; Fri, 4 Jan 2019 18:02:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727439AbfADSCZ (ORCPT ); Fri, 4 Jan 2019 13:02:25 -0500 Received: from foss.arm.com ([217.140.101.70]:47982 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725958AbfADSCW (ORCPT ); Fri, 4 Jan 2019 13:02:22 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D4CCDEBD; Fri, 4 Jan 2019 10:02:21 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 955E83F5D4; Fri, 4 Jan 2019 10:02:18 -0800 (PST) Date: Fri, 4 Jan 2019 18:02:16 +0000 From: Mark Rutland To: Pavel Machek Cc: Marc Zyngier , Kristina Martsenko , linux-arm-kernel@lists.infradead.org, Adam Wallis , Amit Kachhap , Andrew Jones , Ard Biesheuvel , Catalin Marinas , Christoffer Dall , Cyrill Gorcunov , Dave P Martin , Jacob Bramley , Kees Cook , Ramana Radhakrishnan , Richard Henderson , Suzuki K Poulose , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 07/13] arm64: add basic pointer authentication support Message-ID: <20190104180215.GB7157@lakrids.cambridge.arm.com> References: <20181207183931.4285-1-kristina.martsenko@arm.com> <20181207183931.4285-8-kristina.martsenko@arm.com> <20190103202901.GA21564@amd> <681a2835-1a70-f3c3-3534-7b4cf6139cac@arm.com> <20190104093340.GA28150@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190104093340.GA28150@amd> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 04, 2019 at 10:33:40AM +0100, Pavel Machek wrote: > On Fri 2019-01-04 09:21:30, Marc Zyngier wrote: > > On 03/01/2019 20:29, Pavel Machek wrote: > > > On Fri 2018-12-07 18:39:25, Kristina Martsenko wrote: > > >> From: Mark Rutland > > >> > > >> This patch adds basic support for pointer authentication, > > >> allowing userspace to make use of APIAKey, APIBKey, APDAKey, > > >> APDBKey, and APGAKey. The kernel maintains key values for each > > >> process (shared by all threads within), which are initialised to > > >> random values at exec() > > > time. > > > > > > ... > > > > > >> +/* + * We give each process its own keys, which are shared by > > >> all threads. The keys + * are inherited upon fork(), and > > >> reinitialised upon exec*(). + */ +struct ptrauth_keys { + struct > > >> ptrauth_key apia; + struct ptrauth_key apib; + struct ptrauth_key > > >> apda; + struct ptrauth_key apdb; + struct ptrauth_key apga; +}; > > > > > > intstruction_a, data_a, generic_a? Should be easier to understand > > > than "apdb" ... > > > > ... until you realize that these names do match the documentation, > > which makes it even easier to understand how the code uses the > > architecture. > > See how not even the commit log matches the documentation then? The commit message exactly matches the documentation, as it refers to: APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey ... which are the architected names for those registers, in all the documentation. Searching "apga" in the ARM ARM finds all of the relevant information on APGAKey_EL1. Searching "generic_a" finds precisely nothing, as it's a term which you invented, that no-one else has previously used. Likewise for the other key names. > Naming something "apdb" is just bad... Just because the documentation > is evil does not mean it should be followed... It is in no way evil to use the documented names for things. It is unhelpful to make up terminology that no-one else uses. Mark.